1. Field of the Invention
The present invention generally relates to electronic circuits. The present invention more specifically relates to electronic systems operating at high frequencies (approximately ranging from several GHz to several tens of GHz) and requiring a power splitting, respectively a power combination. The present invention especially aims at the forming of radio frequency signal combiners and of radio frequency signal splitters, for radio frequency transceiver chains.
2. Discussion of Prior Art
Radio frequency transceiver chains (RF) are often equipped with frequency combiners/splitters associated with a beam-forming intended for adaptive antennas.
The use of adaptive antennas enables to create a resulting beam in the transmitter or receiver direction and to focus the transmission, for example, to increase the range towards the other system with which the transmission chain communicates.
Adaptive antennas are generally formed of several directional antennas, each individually associated with a transmit or receive channel. The different channels are individually controlled according to the direction desired for the transmission, and are combined (in receive mode) to provide a resulting signal to the processing circuits, or originate (in transmit mode) from a power splitter receiving a signal to be transmitted.
Power combiners or splitters use, in the frequency field to which the present invention applies, conductive line sections associated with impedances and generally are 2 to 1 combiners and 1 to 2 splitters. When the number of channels to be combined or divided is greater than 2, several 2 to 1 combiners or 1 to 2 splitters are cascaded to form 1 to 4, 1 to 8, 1 to 16, or other circuits. Such architectures are set, that is, the number of channels is set for a given electronic circuit. Now, not all channels are necessarily permanently used. This is especially true for adaptive antenna systems where, according to the beam forming, some channels are likely not to be used. In such a case, in transmit mode, part of the power is lost.
Further, this results in particularly bulky systems since the form factor of the electronic circuit depends on the way in which the splitter/combiner is formed.
Similar problems may be encountered in other electronic architectures which operate at high frequency ranges (from several GHz to several tens of GHz). Such is for example the case for clock distribution trees since clock frequencies becomes higher and higher, in particular in the field of microprocessors.